|Publication number||US3985951 A|
|Application number||US 05/594,796|
|Publication date||12 Oct 1976|
|Filing date||10 Jul 1975|
|Priority date||10 Jul 1975|
|Publication number||05594796, 594796, US 3985951 A, US 3985951A, US-A-3985951, US3985951 A, US3985951A|
|Inventors||Robert L. Harris|
|Original Assignee||Niemand Bros. Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (53), Classifications (31), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The invention relates to insulative electrical connectors for conductors and more particularly concerns heat sealable, synthetic polymer resin sleeves or tubes which may be slipped over an electrical connection and fused to the connection.
2. Brief Description of the Prior Art
Prior hereto, sleeves of heat shrinkable materials have been employed to enclose electrical conductors and connections; see for example U.S. Pat. No. 2,027,962. Heat shrinkable sleeves have also been employed for this purpose, which include fusable liners to assist in sealing the sleeve to the conductors or their insulative coverings; see for example U.S. Pat. Nos. 3,243,211; 3,582,457; and 3,814,139.
The present invention is an improvement over the prior art heat shrinkable tubes and processes. First, the sheaths of the present invention may be, and in fact preferably are fabricated from heat-shrinkable polymeric resin material but this is not a necessity as is the case in the prior art. Indeed, the sheath may be constructed according to the invention with non-shrinkable materials, lending greater versatility to their applications where materials of greater rigidity and/or dimensional stability are desired. Consequently, the process of the invention is also advantageous since it is not dependent upon exposing a heat-shrinkable tube to a specific heat-shrinking temperature. Secondly, the prior art sleeves had to be provided in a variety of different diameters because a different sleeve was needed for each of the various conductors and connections of differing gauge. This was necessitated by the more critical need to approximate the diameter or size of the conductor to be covered. A large inventory of sleeves of differing dimension was required to accomplish this. Because the sheaths of the present invention are adaptable to installation on a wider variety of gauges, fewer sizes are required and smaller inventories are required to be maintained. This is a significant economical advantage.
Further, the sheaths and process of the invention insulate the electrical conductors and connections by encapsulating them in a matrix of a polymeric resin foam. This advantageously improves the physical strength of the electrical connection as well as improving the quality of protection afforded to the electrical conductor or connection for which protection is sought. More specifically, an electrical conductor or connection encapsulated in a polymeric resin foam according to the invention has improved dielectric properties in that substitution of a gas for part of the conventional solid polymer insulation results in lowered dielectric constant, dissipation factor and increased dielectric strength. This is particularly advantageous for low frequency electrical systems where it is desirable to make the dielectric constant of insulative material as low as possible. In high-frequency systems the lowered dissipation factor is highly advantageous.
Encapsulation of the electrical conductor or connection in a closed cell polymer resin foam protects the conductor and/or connection from the weather, humidity, galvanic action (particularly where the connection is between diverse metals) adverse thermal conditions (the foam is heat-insulative) rot, mildew, flex fatigue and the like. The foam also serves to cushion the connection, providing more flexible connections and shock absorbing connections. Fire resistant foam formulations may be used to give the electrical connections greater protection against open flame.
The invention comprises a sheath for protecting electrical conductors and connections, which comprises; a tubular body adapted to enclose electrical conductors and connections within a space defined by said body and an expandable, synthetic, polymeric resin foam forming composition disposed in said space.
The invention also comprises a method of protecting electrical conductors and connections from exposure to degradative environments, which comprises; providing a sheath which comprises a tubular body adapted to enclose said electrical conductors and connections within a space defined by said body and an expandable, synthetic, polymeric resin foam forming composition disposed in said space; inserting said electrical conductors and connections into said space; and initiating foaming of said foam forming composition.
FIG. 1 is a cross-sectional, side elevation of a preferred embodiment sleeve of the invention prior to installation on an electrical connection.
FIG. 2 is a cross-sectional, side elevation as in FIG. 1 but after installation.
FIG. 3 is a cross-sectional, side elevation of another sleeve embodiment of the invention after installation on an electrical connection.
For continuity, the preferred embodiments of the invention are best described with reference to the accompanying drawings of FIGS. 1-3.
FIG. 1 is a cross-sectional side elevation of a sheath embodiment 5 which comprises a tubular body 10 closed at one end by integral end wall 11. The body 10 and integral end wall 11 may be fabricated from any convenient rigid, semi-rigid or flexible material. Representative of such materials are metals such as iron, steel, aluminum, tin and the like; cellulose forms such as paper, wood and the like; and polymeric materials both natural and synthetic such as cellulose acetate rubber, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymers, polyurethane elastomer, polystyrene, polyvinyl chloride, butadiene-acrylonitrile rubber, polyimide, polyamide, polyacrylic and the like. Advantageously the material of body 10 and end wall 11 is electrically non-conductive and thermally conductive. Preferably body 10 and end wall 11 are weather-proof or treated to make them weather-proof, i.e.; resistant to the effects of water, heat, cold and sunlight. Preferably, the body 10 and end wall 11 are fabricated from a flexible, oriented thermoplastic having a heat activatable memory which upon exposure to a temperature above room temperature will shrink in dimension a predetermined amount. Representative of such preferred thermoplastics are fluorinated ethylene and propylene polymers, polyethylene terephthalate, irradiated and heat deformed polyolefins and the like. Most preferred is the polyethylene terephthalate. The tubular bodies 10 may be fabricated by conventional extrusion and laminating techniques; see for example U.S. Pat. No. 3,491,799.
The body 10 and end wall 11 define space 12 which is adapted to receive, upon insertion, an electrical connection as shown by twisted conductors 16, 18. Space 12 also has disposed therein an expandable, synthetic, polymeric resin foam forming composition 14. Although the composition 14 may be disposed in space 12 in any convenient manner, it is preferably formulated and disposed so as to adhere to the inner surface of the containing body 10 and/or wall 11. Foam forming composition 14 may be any expandable composition which upon expansion forms a cellular plastic foam having dielectric properties. Any of the well known, synthetic polymeric resin foams which are initiated by actinic radiation are useful in the sheaths of the invention. Preferably the foams formed are closed cell foams.
Preferred compositions 14 are dispersions of polymer resins such as polyvinyl chloride, polyethylene, polypropylene, natural rubber, butadiene-acrylonitrile rubber, styrene-butadiene copolymers, polyamides, polyesters and the like in admixture with conventional blowing agents characterized by their decomposition at known temperatures to generate gaseous products. Preferred blowing agents are those which decompose under actinic radiation to produce nitrogen gas. Nitrogen gas is the preferred blowing gas because of its non-oxidative properties. Representative of such blowing agents are azodicarbonamide, 4,4'-oxybis (benzenesulphon hydrazide), dinitrosopentamethylene tetramine, tris [m-azidosulfonylbenzene] isocyanurate, tris [p-azidosulfonylbenzene] isocyanurate, p-toluenesulfonyl hydrazide, 2,2'-azobisisobutyronitrile and the like.
The proportion of blowing agent may be varied according to known techniques to cause a foam expansion of up to about 10 times. The techniques of preparing such blowing agents in polymer resin dispersions is well known; see for example Goldberg and Bolabanov, Zh. Organ. Kim., 1,(9), 1604-6, (1965) (Russ.). In general the blowing agent is blended into the polymer material. Blending may be carried out by milling on a conventional rubber mill or by dissolving in a solution of the polymer. Other methods of mixing the blowing agents and polymer resins will be apparent to those skilled in the art. Additives such as fillers, extenders, stabilizers, surfactants, dyes, plasticizers, fire retardants and the like may also be used to compound the compositions 14 with desired specific properties. Representative of polymeric resin foam forming compositions which may be used to coat the inside surface of a polyethylene terephthalate tubular body are the following. All parts are by weight.
An appropriate vessel is charged with from 50 to 50.4 parts of a thermoplastic polyamide resin (Versalon 750; General Mills, Inc., Minneapolis, Minn.), 30.0 parts of isopropanol and 15.0 parts of toluene. The mixture is blended and 4.5 parts of micropulverized asbestos and from 0.1 to 0.5 parts of p-toluenesulfonyl hydrazide is added with stirring. The resulting mixture is a polyamide foam forming composition which is activatable to obtain a closed cell polyamide foam by heating circa 200° F. to 250° F. Depending on the proportion of p-toluenesulfonyl hydrazide, the density of the foam obtained may be between about 2 to 5 pounds per cubic foot, expansion being from 2 to 10 times the original volume of the foam forming composition.
An appropriate vessel is charged with from 56.8 to 57.2 parts of a thermoplastic polyester dissolved in 38.0 parts of methyl ethyl ketone [Bostik 7240; U.S.M. Corporation, Middletown, Mass.; 14,000 cps consistency (Brookfield at 25° C.)]. With stirring, 4.7 parts of silica (Cab-O-Sil) and from 0.1 to 0.5 parts of 2,2'-azobisisobutyronitrile is added to obtain a polyester foam forming composition.
The compositions 14 are preferably activated to foam by exposure to actinic radiation. If the body 10 is permeable to ultraviolet radiation, composition 14 may include a blowing agent decomposable by exposure under a source of ultraviolet. Preferably, the blowing agent decomposes to form foam under infra-red radiation, i.e.; heat.
The method of the invention comprises inserting electrical conductors and/or connections into the sheath 5 of the invention as illustrated in FIG. 1 showing conducting wires 16 and 18 inserted with parts of their insulated portions 20 and 22 into space 12. A connection is made between conductors 16 and 18. In the next step of the method of the invention, the foam forming composition 14 is activated to form a polymeric resin foam. Illustratively, if the foam forming composition 14 is one of preparations 1 and 2, supra., coated at a thickness of about 15/1000th of an inch on the inner surface of a tube of polyethylene terephthalate, activation occurs by applying a heat of circa 200° F to 250° F. to the sheath 5. The composition 14 melts or fuses, the blowing agent decomposes to generate nitrogen gas and the composition 14 expands to form a cellular polymeric resin foam 24 as shown in FIG. 2. FIG. 2 is a cross-sectional, side elevation as seen in FIG. 1 but after activation of the foam forming composition 14 to encapsulate conductors 16, 18 in polymer resin foam 24. Upon cooling, the foam solidifies, entrapping the nitrogen gas bubbles. Since the body 10 was a heat-shrinkable material in our illustration, the sheath 5 is also shown of reduced dimension in FIG. 2. This advantageously forms a tight bond between wall 10 and foam 24. The foam 24 encapsulation is weather-proofed by the bonded wall 10. The wall 10 also provides a physical protection for low density foams, which are particularly preferred for their lower dielectric constant, dissipation factor and increased dielectric strength. By low density foam, I mean a polymeric resin foam having an average density of about 2-4 pounds per cubic foot. Those skilled in the art are well aware of the techniques for forming foams of such density.
Those skilled in the art will also appreciate that many variations of the preferred embodiments described above may be made without departing from the spirit and scope of the invention. For example, the tubular sheath of the invention may have two open ends as shown installed in FIG. 3. FIG. 3 is a cross-sectional, side elevation of an alternate embodiment sheath 6 having both ends open and foamed in place on electrical connection 16, 18.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2186793 *||27 Nov 1937||9 Jan 1940||Anaconda Wire & Cable Co||Electric cable|
|US3243211 *||23 Jul 1962||29 Mar 1966||Raychem Corp||Connector with fusible material|
|US3420363 *||13 Apr 1966||7 Jan 1969||Us Plywood Champ Papers Inc||Foams demonstrating thermal memory and products made therefrom|
|US3836702 *||3 Apr 1973||17 Sep 1974||Plummer Walter A||Means for sealing and protecting a cable splice|
|DE1920637A1 *||19 Apr 1969||29 Oct 1970||Ver Draht & Kabelwerke Ag||Telephone cable joint with plastic foam - filled sleeve|
|NL6803179A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4105481 *||7 Jun 1977||8 Aug 1978||Raychem Corporation||Encapsulation method for electrical elements|
|US4179319 *||24 Jan 1977||18 Dec 1979||Raychem Corporation||Heat recoverable article and methods using same|
|US4232712 *||25 Sep 1978||11 Nov 1980||Raychem Limited||Heat-recoverable articles|
|US4260570 *||11 May 1979||7 Apr 1981||Block Drug Company Inc.||Method and apparatus for making a vaginal cleaning device|
|US4269638 *||10 Oct 1979||26 May 1981||The Okonite Company||Method of manufacturing a sealed cable employing a wrapped foam barrier|
|US4270961 *||10 Oct 1979||2 Jun 1981||The Okonite Company||Method of manufacturing a sealed cable employing an extruded foam barrier|
|US4314954 *||6 Sep 1979||9 Feb 1982||Bakelittfabrikken A/S||Method of producing molded bodies of expanded plastic|
|US4386628 *||20 Nov 1980||7 Jun 1983||Pro-Tech Advisory Services Limited||Maintenance lining of passageways|
|US4555284 *||8 Feb 1983||26 Nov 1985||Siemens Aktiengesellschaft||Method of using a foamable hot-melt adhesive for sealing|
|US4559274 *||18 Apr 1983||17 Dec 1985||Ford Motor Company||Composite components of sandwich construction|
|US4600261 *||12 Oct 1982||15 Jul 1986||Raychem Corporation||Apparatus and method for protection of electrical contacts|
|US4640978 *||15 Jul 1985||3 Feb 1987||Minnesota Mining And Manufacturing Company||Foam-sealed electrical devices and method and composition therefor|
|US4647716 *||6 Nov 1984||3 Mar 1987||Sigmaform Corporation||Article having heat expandable sealing member|
|US4690831 *||18 Jun 1986||1 Sep 1987||Raychem Corp.||Protective article|
|US4749420 *||12 Dec 1986||7 Jun 1988||The United States Of America As Represented By The Secretary Of The Navy||Method of making cable assembly for use in an antenna element assembly|
|US4864725 *||18 Apr 1988||12 Sep 1989||Raychem Corporation||Electrical connector and method of splicing wires|
|US4865905 *||9 Dec 1988||12 Sep 1989||Raychem Corporation||Article for protection of a substrate|
|US4907623 *||3 Jun 1988||13 Mar 1990||Plastics Tubes Company||Heat-shrinkable insulating tube|
|US4923537 *||9 Feb 1989||8 May 1990||Honda Giken Kogyo Kabushiki Kaisha||Method for shaping a resin coating of a wire harness|
|US5113039 *||9 Jan 1991||12 May 1992||Cooper Industries, Inc.||Flexible cord with high modulus organic fiber strength member|
|US5140746 *||21 Aug 1989||25 Aug 1992||Raychem Corporation||Method and device for making electrical connector|
|US5151239 *||22 Mar 1991||29 Sep 1992||King Technology Of Missouri Inc.||Method of making a wire junction encapsulating wire connector|
|US5229184 *||24 Feb 1989||20 Jul 1993||Albany International Corporation||Heat shrinkable fibres and products therefrom|
|US5281763 *||3 Jul 1990||25 Jan 1994||Raychem Gmbh||Cable blocking|
|US5357057 *||21 Aug 1992||18 Oct 1994||Raychem Corporation||Protected electrical connector|
|US5514836 *||11 Oct 1993||7 May 1996||Raychem S.A.||Electrical connector|
|US5639992 *||18 Oct 1994||17 Jun 1997||Raychem Corporation||Method and device for making a protected electrical connector|
|US5641943 *||12 Aug 1994||24 Jun 1997||Sumitomo Wiring Systems, Ltd.||Method and apparatus for connecting electric wires to each other|
|US5672846 *||2 Jun 1995||30 Sep 1997||Raychem Corporation||Electrical connector|
|US5814768 *||11 Dec 1996||29 Sep 1998||Commscope, Inc.||Twisted pairs communications cable|
|US5917151 *||29 Aug 1997||29 Jun 1999||Ut Automotive Dearborn, Inc.||Multi-shot molds for manufacturing wire harnesses|
|US5973265 *||29 Aug 1997||26 Oct 1999||Lear Automotive Dearborn, Inc.||Wire harness with splice locators|
|US6011318 *||16 Apr 1998||4 Jan 2000||Lear Automotive Dearborn, Inc.||Wire harness for vehicle seat|
|US6027679 *||29 Aug 1997||22 Feb 2000||Lear Automotive Dearborn, Inc.||Method for securing a wire harness to a surface|
|US6054651 *||19 Nov 1996||25 Apr 2000||International Business Machines Corporation||Foamed elastomers for wafer probing applications and interposer connectors|
|US6069319 *||22 Jul 1997||30 May 2000||Lear Automotive Dearborn, Inc.||Foamed-in harnesses|
|US6071446 *||29 Aug 1997||6 Jun 2000||Lear Automotive Dearborn, Inc||Method for centering wire harness in mold|
|US6086037 *||29 Aug 1997||11 Jul 2000||Lear Automotive Dearborn, Inc||Mold for assembling and forming wire harness|
|US6107569 *||12 May 1998||22 Aug 2000||Shields; Scott D.||Foam wire harness in a pillar|
|US6120327 *||29 Aug 1997||19 Sep 2000||Lear Automotive Dearborn, Inc.||Foam wire harness with shape memory|
|US6126228 *||11 Sep 1997||3 Oct 2000||Lear Automotive Dearborn, Inc.||Wire harness foamed to trim panel|
|US6403889||31 May 2000||11 Jun 2002||Tyco Electronics Corporation||Bi-layer covering sheath|
|US7243987 *||31 Jan 2006||17 Jul 2007||Nissan Technical Center North America, Inc.||Apparatus and method for noise reduction in a vehicle|
|US7364478||6 Sep 2006||29 Apr 2008||K.S. Terminals, Inc.||Connector and method for manufacturing and connecting wire|
|US7954235 *||20 Oct 2009||7 Jun 2011||Delphi Technologies, Inc.||Method of making a seal about a copper-based terminal|
|US20040265566 *||30 Jun 2003||30 Dec 2004||Lear Corporation||Interior trim system and method for making same|
|US20070182213 *||31 Jan 2006||9 Aug 2007||Nissan Technical Center North America, Inc.||Apparatus and method for noise reduction in a vehicle|
|US20070224891 *||6 Sep 2006||27 Sep 2007||K.S. Terminals, Inc.||Connector and method for manufacturing and connecting wire|
|US20110067239 *||24 Mar 2011||Delphi Technologies, Inc.||Method of making an improved electrical connection for a sealed cable core and a terminal with conformal coating|
|USRE37340||16 Jul 1997||28 Aug 2001||King Technology Of Missouri, Inc.||Wire junction encapsulating wire connector and method of making same|
|EP0443694A1 *||25 Mar 1986||28 Aug 1991||Raychem Corporation||Protective article|
|WO1981000356A1 *||13 Aug 1980||19 Feb 1981||R Strickman||Polymeric drug delivery applicators|
|WO1994009531A1 *||11 Oct 1993||28 Apr 1994||Raychem Ltd||Electrical connector|
|U.S. Classification||174/138.00F, 138/141, 428/319.7, 264/DIG.5, 138/146, 174/110.00F, 156/79, 428/314.4, 174/84.00R, 264/46.9, 264/230, 264/54, 174/DIG.8, 264/46.7, 156/86, 138/178|
|International Classification||H01B7/285, H01B17/58, H01R4/22, H01R13/52|
|Cooperative Classification||Y10T428/249976, Y10T428/249992, Y10S174/08, Y10S264/05, H01B7/2855, H01B17/58, H01R4/22, H01R13/5216|
|European Classification||H01B17/58, H01R4/22, H01B7/285F|
|6 Jun 1985||AS||Assignment|
Owner name: J. L. CLARK MANUFACTURING CO., 2300 SIXTH STREET,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:NIEMAND BROS., INC.;REEL/FRAME:004413/0951
Effective date: 19850502